1. Field of the Invention
The present invention relates to a heat exchanger for use as, e.g., a recuperator (high-temperature regeneratve heat exchanger) for a gas turbine.
2. Description of the Related Arts
A conventional recuperator for a gas turbine has been constructed as shown in FIG. 20 by way of example.
FIG. 19 is a top plan view of an element 23 of the recuperator, with FIG. 20 being a schematic longitudinal section of the recuperator having a multiplicity of elements 23 which are stacked one upon another.
The element 23 of the recuperator consists of a pair of dish-shaped plates 24 and 25 which are oppositely disposed on top of the other, the plates each comprised of a press mold of a stainless steel plate having an inlet 6 and an outlet 7 formed at opposed ends, with raised portions 26 at the rims of the inlet 6 and outlet 7. The multiplicity of elements are placed one upon another such that their respective inlets and outlets are in communication with one another. Reinforcement plates 27 and 28 having an increased thickness are arranged at vertically opposed ends in the stacked direction, with the reinforcement plate 27 on one hand having a pair of openings 13 in communication with the inputs 6 and the outlets 7. The plates 24 and 25 hitherto used have internal and external surfaces with high-temperature resistant brazing materials.
With such components being assembled, the entirety is introduced into a furnace at high temperature to melt the brazing materials, and the molten brazing materials are then cooled and solidified so that the components are integrally brazed to each other. A second fluid 11a is delivered through the opening 13 of the reinforcement plate 27 to the inlet 6 of each of the elements 23. The second fluid 11a then flows through flat second flow passages 11 defined between internal surfaces of each plate pair and via the outlet 7 to the exterior. A first fluid 10a flows through first flow passages 10 defined between external surfaces of adjacent plate pairs such that heat exchange takes place between the first fluid 10a and the second fluid 11a. At that time, the second fluid 11a is in the form of a low-temperature high-pressure air (of the order of 200xc2x0 C.) delivered into the interior of each element 23 whilst the first fluid 10a is a high-temperature low-pressure gas (of the order of 700xc2x0 C.) flowing therethrough.
Since the gas turbine has a circular periphery, the internally flowing high-temperature gas flows through the tubular interior having a circular section. However, the periphery of the conventional recuperator for a gas turbine is generally rectangular in section, causing mismatching therebetween and impeding a reduction in size.
The conventional recuperator suffers deficiencies that it needs a multiplicity of dish-shaped plates, i.e., increased number of components, making the assembly troublesome. There is also a need to use brazing materials resistant to high temperature of 700xc2x0 C. or above on the internal and external surfaces of the plates making up each element, i.e., a need for a large quantity of expensive brazing materials.
It is therefore the object of the present invention to solve the above problems.
In order to achieve the above object, according to an aspect of the present invention there is provided a cylinder-type heat exchanger comprising an inner cylinder and an outer cylinder which are concentrically arranged; and one or more cells disposed between the inner and outer cylinders and spirally wound therebetween; the one or more cells each including a first plate and a second plate in pairs which are in contact with each other; wherein the first and second plates in pairs are each provided with a plurality of circumferentially spaced apart inlets and outlets at opposed ends in the axial direction of the inner cylinder, the plurality of inlets lying within recessed portions formed oppositely in the first and second plates such that the plurality of inlets register with one another and that the plurality of outlets register with one another; wherein communication portions are arranged between circumferentially adjoining inlets and between circumferentially adjoining outlets of the first plate and the second plate; wherein the first and second plates in pairs are provided on their confronting sides with a first flow passage for communication of a first fluid extending in the axial direction, the first and second plates in pairs being provided on their non-confronting sides with a second flow passage for communication of a second fluid extending from the inlets to the outlets in the axial direction; and wherein the second plate of one of radially adjoining cells and the first plate of the other of the radially adjoining cells are in contact with each other at their opposed edges in the axial direction, the recessed portions of the first and second plates confronting each other to form small tank portions for outflow and inflow of the second fluid.
Preferably, the periphery of the outer cylinder is provided with a plurality of openings for outflow and inflow of the second fluid which communicate with the inlets and outlets of the one or more cells.
Preferably, the first plate and the second plate in pairs of each of the one or more cells are securely inlet-to-inlet and outlet-to-outlet welded to each other, the second plate of one of adjoining cells and the first plate of the other of the adjoining cells being securely welded to each other at their opposed edges in the axial direction, with the plates being substantially free from join at remaining portions.
Preferably, the one or more cells are joined at their ends in the winding direction to the periphery of the inner cylinder in a circumferentially spaced apart relationship.
Preferably, the first and second plates in pairs of each of the one or more cells form corrugations between the inlets and the outlets such that their ridges incline relative to the axis and that the ridges of corrugation of the first plate intersect the ridges of corrugation of the second plate.
Preferably, the first and second plates in pairs form semi-corrugations at the communication portions such that their ridges incline relative to the axis and that the ridges of the semi-corrugation of the first plate intersect the ridges of the semi-corrugation of the second plate.
Preferably, based on thermal expansion and contraction of the cell, the inner cylinder is capable of circumferentially relatively rotating relative to the outer cylinder.
Preferably, the first fluid is a high-temperature gas and the second fluid is a low-temperature gas, the second fluid surrounding the periphery of the outer cylinder such that it is led from the plurality of openings in the periphery of the outer cylinder into the interior of each of the one or more cells.
The internal pressure of the second fluid is preferably larger than that of the first fluid.